Control Flow & Section Topology

This page follows the Ktory design principles, which distinguish current contracts from longer-term goals.

Control Flow and Sections

The root executes in source order and skips named section bodies. Use canonical indentation: a named section’s body is deeper than === Label ===; returning to the header’s indentation resumes root content.

: The story begins.
=> Greeting
: Continue the main story.
-> end

=== Greeting ===
  Alice: Welcome.
  -> return

=> Greeting establishes a return position, and -> return resumes at “Continue the main story.” Replacing the call with -> Greeting clears the call stack, so no return position may be assumed.

Instruction	Meaning
-> Label	Clear the call stack and jump to the target section
=> Label	Record a return position and call the target section
-> return	Pop a call frame; an empty stack is a control-flow error
-> break	Exit the nearest active loop and continue after it
-> end	End the file in root; in a named section, clear the stack and resume at the first subsequent root node

Reaching a named section’s end is equivalent to -> end there; it does not implicitly return to the caller. Write -> return when a return is intended. A host can select an entry with Start(entryLabel: "Greeting"), but that does not establish a call frame: the example above must be called through the root to execute its final return.

Forward-only does not prohibit backward jumps or loops. It means earlier external side effects are not automatically undone. Re-entering a beat dispatches its presentation or state decorators again.